In molding using a mold for molding a thermosetting resin molding material, a mold releasing agent contained in the thermosetting resin molding material oozes out to the inside surface of the mold to exhibit a mold-releasing action. However, when such a molding step is repeated, inconveniences occur that the releasing property of the molded products is decreased and the appearances of the molded product is poor. Those inconveniences are considered to be caused by that the releasing agent contained in the molding material oozes onto the inside surface of the mold and gradually deteriorates while successively accumulating on the surface of the mold by repeating the molding step, whereby the soiled material layer which lost the effect as the mold releasing agent is formed.
To solve such a problem, a cleaning work of the mold is performed at the stage of the formation of the soiled material layer which is the deteriorated mold releasing agent layer. For example, it is hitherto carried out that a thermosetting melamine resin molding material is placed in the mold, molded, and cured to integrate the soiled material on the inside surface of the mold with the molded product in a body, and the molded material integrated with the soiled material in a body is taken out of the mold, thereby the inside surface of the mold is cleaned. However, in such a cleaning method, formalin is by-produced as a condensation product of the thermosetting melamine resin molding material to generate unpleasant odor, and also, the removal of the molded product is not easy and takes much time. Therefore, the working environment greatly deteriorates, resulting in decreasing the cleaning workability.
Thus, recently a method is proposed and is partially practically used, wherein an unvulcanized rubber compound is used in place of the above-described thermosetting melamine resin molding material, the unvulcanized rubber compound is vulcanized in the mold to form a vulcanized rubber, the soiled material on the inside surfaces of the mold is integrated with the vulcanized rubber in a body in forming the vulcanized rubber, and by taking out the vulcanized rubber from the mold, the inside surface of the mold is cleaned.
However, the composition of the thermosetting resin molding material differs according to the required characteristics, there are many kinds of thermosetting resin molding materials, and the state of soiling the mold caused by repeating molding and the components of the soiled material are widely various. In particular, where a soiled material is formed on the inside surfaces of a mold in repeatedly conducting molding using a molding material comprising a biphenyl epoxy resin, a polyfunctional epoxy resin, or a dicyclopentadiene epoxy resin as the main component in place of a novolak epoxy resin conventionally used, there is a problem that the soiled material is baked severely to the inside surfaces of a mold, and it is impossible to completely remove the soiled material in the conventional cleaning method using the unvulcanized rubber compound.